Dropbox

Basically, you store files in a Dropbox account, which can then be edited on all of your devices. So, if you work on a file on your laptop, any changes you save will synchronise on your PC and mobile. There is a limit to the storage space, but you can upgrade to a paid version if you need to.

Trello

Project manage your business to within an inch of its life with Trello, the free application for creating work boards, lists, cue cards, setting reminders and a whole lot more. Perfect for organising work, events and ideas.

MailChimp

So much more than an email service, MailChimp lets you create customised and branded newsletters and provides you with detailed reports on how they go down with your audience. A good way to improve how you talk to your clients.